1. Field of the Invention
This invention relates to a shield wire having a function for shielding the wire from an electromagnetic noise.
2. Description of the Related Art
A wiring harness for supplying electric power and control signals from a power source and a controller to electronic apparatuses, such as various lamps and various motors mounted in an automobile as a vehicle is wired. The wiring harness includes a plurality of electric wires and terminals connected to ends of the electric wires. The wiring harness includes a shield wire as one of the electric wires (shown in FIGS. 9, 10, refer Patent documents 1, 2).
The shield wire 101A shown in FIG. 9A includes a covered wire 120 provided by covering an electrical conductive core 102 with an insulation cover 103, a braid shield 104 provided around an outer surface of the covered wire 102, and an insulating sheath 105 covering an outer surface of the braid shield 104. The braid shield 104 is formed into a tube shape by braiding metal element wires wound in respective bobbins 200 to cross each other as shown in FIG. 9B. The braid shield 104 is connected to a required earth circuit. The shield wire 101A structured as described above flows an external noise, which would go into the covered wire 120, through the braid shield 104 to the earth circuit so that it is prevented that the external noise goes into the core 102 of the covered wire 120.
The shield wire 101B shown in FIG. 10 includes the covered wire 120 provided by covering the electrical conductive core 102 with the insulation cover 103, a drain wire 107, a metal foil shield 106 wound around both the outer surface of the covered wire and the drain wire 107, and the insulating sheath 105 covering an outer surface of the metal foil shield 106. The drain wire 107 contacting with the metal foil shield 106 is connected to the required earth circuit. The shield wire 101B structured as described above flows the external noise, which would go into the covered wire 120, through the metal foil shield 106 and the drain wire 107 to the earth circuit so that it is prevented that the external noise goes into the core 102 of the covered wire 120.
The shield wire 101C shown in FIG. 11 includes a wire bundle 108 bundling a plurality of covered wires and the drain wire, and a strip-shaped conductive foil sheet 110 wound spirally around an outer surface of the wire bundle 108. The covered wire (not shown) is structured as same as the covered wire 120 forming the shield wire 101B shown in FIG. 10. The conductive foil sheet 110 includes a thin conductive layer and a thin insulation layer provided on the conductive layer so as to be formed into a relatively thin strip shape. The conductive foil sheet 110 is wound around the wire bundle 108 so as to make the conductive layer touch the drain wire. The drain wire touching the conductive layer is connected to the required earth circuit. The shield wire 101C structured as described above flows the external noise, which would go into the covered wire 120, through the conductive layer of the conductive foil sheet 110 and the drain wire to the earth circuit so that it is prevented that the external noise goes into the core of the covered wire. Refer Patent documents of Japan Published Patent Application No. 2003-115223 and published Japan Utility Model Application No. H06-41028.